import java.util.LinkedList;

public class ListNode {
    int val;
    ListNode next;

    public ListNode() {
    }

    public ListNode(int val){
        this.val=val;
    }

    public ListNode(int val, ListNode next){
        this.val = val;
        this.next = next;
    }

//    public void addAtHead(int val) {
//        ListNode newNode = new ListNode();
//        newNode.next = this.next;
//        newNode.val = val;
//        this.next = newNode;
//    }

}
